WO2003045268A1 - Ceramic dental implant - Google Patents

Abstract

The invention relates to a dental implant comprising an anchor part (12) for anchoring said implant in the bone and a mounting part (18) for receiving a prosthetic superstructure. According to the invention, the anchor part (12) and the mounting part (18) are configured in one piece from a zirconium oxide-based material and at least sections of the external surface of at least the anchor part are pre-treated using a subtractive removal method or are provided with a coating, which supports ossification.

Description

 CERAMIC DENTAL IMPLANT

The invention relates to a dental implant with an anchoring part for anchoring in the bone and with a mounting part for receiving an element to be applied, such as an abutment or a crown, bridge or prosthesis construction.

Dental implants have been used successfully for more than 10 years. The majority of the dental implants currently used are made of titanium, since titanium is sufficient has a low modulus of elasticity and a relatively high strength. It is also of particular importance that titanium as the implant material is used to achieve a safe composite osteogenesis if the surface is suitably designed (eg roughened by sandblasting). This means that after achieving primary stability by screwing into the bone, the titanium implants safely ossify within a healing time of about 3 to 4 months, so that a permanent bond between the anchoring part screwed into the bone and the bone is ensured. Usually two-part implants are used for this, for which there are basically two options.

According to a closed, subgingival system, the anchoring part of the implant is sunk to the level of the bone crest so that the mucoperiosteal cover can be sewn over the implant. A disadvantage here is the necessary second operation at the end of the healing phase in order to then be able to apply a build-up part and the desired prosthesis or crown to it.

In contrast, a secondary operation can be avoided with the open, transgingival system, in which the anchoring part of the implant is sunk up to approx. 3 mm above the bone crest at the mucosal level. The edges of the wound can be directly adapted to the implant neck, which results in a primary soft tissue closure on the implant.

Such a two-part implant construction for an open transgingival system is marketed, for example, by the Institut-Straumann AG, Waldenburg / Switzerland under the name ITI ^® DENTAL IMPLANT SYSTEM. Both the anchoring Part or primary part, which is implanted transgingival, as well as the associated abutments are made of pure titanium. To ensure good ossification, the titanium surface is either roughly sandblasted or coated with titanium by thermal spraying. Both surfaces ensure good ossification or composite osteogenesis.

Prosthetic elements such as bridges or crowns are then usually screwed or cemented onto the abutment of such implants with the interposition of so-called abutments. Recently ceramic abutments have also been developed for this purpose, which are applied to the abutment.

Ceramic abutments have particular advantages when later adapting the superstructure, such as bridges or crowns, to the abut ent. They are easy to grind and enable the construction of constructions according to conventional procedures familiar to the dentist. Ceramic abutments have particular advantages, in particular due to the fact that their color can be approximated to the natural tooth color. In recent times, zirconium oxide abutments have also been developed, which are characterized by particularly high strength.

Although such a system consisting of a two-part implant with anchoring part and abutment part, abutment and prosthetics applied thereon allows a good adaptation to the geometric conditions for various indications, the large number of components involved is fundamentally disadvantageous for the mechanical stability of the overall system. Each additional connection also leads to possible starting points for bacterial s that can cause periodontitis or gingivitis in the cleft.

For aesthetic reasons, it would be desirable, especially in the front, visible area, to make all transgingival parts, including the anchoring part, from ceramic. However, there is a screw connection between metal (anchoring part made of titanium) and ceramic (mounting part) etc. not feasible due to the differences in the coefficients of thermal expansion. In contrast, anchoring parts made of ceramic could not prevail, since these usually do not have the desired mechanical stability.

Recently, zirconium oxide ceramics have also become available which have extremely high strength, in particular if the shaped bodies are hot isostatically pressed or hot isostatically compressed. Such a zirconium oxide ceramic, which contains about 92.1-93.5% by weight of ZrO ₂ , 4.5-5.5% by weight of Y ₂ O ₃ and 3.8-2.2% by weight of Hf0 ₂ , is known for example from US 6,165,925.

However, the use of zirconium oxide ceramic as a material for producing the anchoring part of an implant does not appear possible, since it is necessary for the zirconium oxide ceramic to have sufficient mechanical stability to produce it in a highly dense manner, with practically no measurable porosity, while at the same time resulting in a smooth, extremely hard surface.

Such a material is bioinert, so that no compound osteogenesis is to be expected, which is why this material is considered is not considered suitable for producing the anchoring part of an implant.

DE 195 30 981 AI discloses a prefabricated all-ceramic implant superstructure made of zirconium dioxide for the tooth-colored build-up of implant-supported artificial crown stumps. Certain advantages with regard to the aesthetics of zirconium oxide ceramics and a possibly simplified preparation in the construction of the superstructure are made possible, but this implant construction also has the fundamental disadvantages associated with multi-part implant constructions. Since the actual implant is made of titanium, problems still arise in the connection area between the implant and the superstructure made of zirconium oxide ceramic.

The invention is therefore based on the object of avoiding the disadvantages of the prior art and of creating an improved dental implant with which a high mechanical stability of the overall system is ensured and at the same time the advantages of ceramic can be used, in particular in the field of vision. A suitable manufacturing process for this purpose is also to be specified.

This object is achieved according to the invention by a dental implant with an anchoring part for anchoring in the bone and with a structural part for receiving an element to be applied, the anchoring part and structural part being formed in one piece from a material based on zirconium oxide and the surface at least partially either by a subtractive, ablative method is pretreated or with a treatment Stratification is provided, which supports ossification.

Furthermore, this task is solved by a method for producing a dental implant, in which a base body with an anchoring part for anchoring in the bone and with a structural part for receiving an element to be applied is first provided in one piece from a material based on zirconium oxide, and then at least the anchoring part its outer surface is at least partially pretreated by a subtractive, ablative process or is provided with a coating that supports ossification.

The object of the invention is completely achieved in this way.

Surprisingly, it has been shown that a one-piece dental implant with an anchoring part and a build-up part can be produced in this way, which consists of a material based on zirconium oxide and which nevertheless ensures good ossification during the healing time.

The one-piece design of the implant, which combined with the high strength of zirconium oxide ceramic, ensures a high stability of the overall system is a particular advantage. At the same time, there is the particular advantage that the build-up part approximates the natural tooth color and thus, in particular in the field of vision, the production of completely natural-looking ceramic reconstructions allows. The structural part can also be ground immediately, which enables simple and advantageous adaptation of the further elements to be applied. Additional abutments may not be necessary.

From DE 40 12 731 AI different methods for surface treatment of implants are known in principle in order to produce a defined rough surface, however, the invention is not suggested by this, since this document relates only to the treatment of metallic implants and no reference from this can be removed, which would suggest to a person skilled in the art to develop a one-piece implant based on zirconium oxide.

From DE 28 38 759 AI it is also known in principle to provide an implant made of metal, plastic or ceramic with a layer system which consists of a passivating layer and / or several physiologically active layers. In particular, a passivating layer made of silicon nitride and a physiologically active layer made of calcium fluoride, made of α-alanine, made of carbon or the like is considered.

However, this also does not suggest the invention, since this publication only deals in general with possible coatings of implants and no information is conveyed to the person skilled in the art to create a one-piece implant based on zirconium oxide.

The implant according to the invention is preferably used transgingival. So is the soft tissue attachment with training the biological breadth is no longer disturbed by a second intervention as with mucous membrane-healing systems.

According to the invention, after the implantation, an initial restoration is made possible by attaching a temporary restoration directly to the abutment. For this purpose, once sufficient primary stability has been achieved, for example by screwing the anchoring part into a bone hole, only measures have to be taken to avoid, in particular, shear movements in the subsequent healing time. In the case of several implants, this can be ensured by interlocking, while in the case of individual implants this is ensured in part by gluing to adjacent teeth or prosthetic parts.

The anchoring part preferably has a threaded section.

In this way, the implant according to the invention can be implanted with the necessary primary stability, so that an initial provision can be achieved immediately after the implantation.

According to a further embodiment of the invention, the anchoring part is at least partially roughened or microstructured on its outer surface by an ablation process.

Such a surface structuring ensures that the otherwise bio-inert zirconium oxide material can undergo composite osteogenesis with the bone substance. In order to achieve good composite osteogenesis, it is preferred if the dental implant in the area of the anchoring part has a maximum roughness depth between 1 and 20 μm, preferably between 2 and 15 μm, in particular between 4 and 12 μm, particularly preferably between 6 and 12 μm.

In principle, blasting treatment, for example by sandblasting (with corundum), by blasting with boron carbide particles, or by high-pressure water jets, can be used.

The problem with such a treatment is the high hardness of the zirconium oxide ceramic. A significantly improved roughness depth can therefore be achieved, for example, by using a hard material for blasting, such as boron carbide particles, which is, however, quite expensive.

For this reason, chemical processes, in particular etching processes, are also considered as an alternative, which in some cases can be used as a supplementary treatment for a previous mechanical treatment.

In addition, laser-assisted processes are also suitable for such ablation processes.

A blasting treatment, for example by sandblasting with Al ₂ O ₃ , and then an etching treatment with phosphoric acid, sulfuric acid, hydrochloric acid or mixtures thereof is particularly preferred. The blasting treatment can be carried out at a pressure between about 1 bar and 10 bar, preferably between 2 and 6 bar, in particular between 3 and 5 bar.

In particular, an etching treatment with phosphoric acid of 10 to 90% by volume, preferably 15 to 50% by volume, in particular 20 to 40% by volume, is preferred as an aftertreatment to a blasting treatment.

The etching can be carried out, for example, over a period of 10 seconds to 10 minutes, preferably from 10 to 120 seconds, in particular from about 15 to 60 seconds.

An etching treatment is expediently followed by a cleaning step, for example by rinsing in a NaCl solution and then rinsing in deionized water.

With dental implants pretreated in this way, in particular in the area of the anchoring part, reliable composite osteogenesis can be achieved.

According to a further embodiment of the invention, the anchoring part is at least partially provided with a bioactive coating on its outer surface.

This can be, for example, silanization or hydroxylation, which also supports osteogenesis.

According to a further embodiment of the invention, the anchoring part is at least partially with a metallic or ceramic coating or with a cermet coating.

In this way too, a certain surface structuring can be created to support composite osteogenesis.

Here, the anchoring part can be provided with a coating, for example by thermal spraying, by CVD or by PVD.

A coating made of titanium or a titanium alloy, which can be applied, for example, by thermal spraying, is considered to be advantageous.

With such a coating, the proven biocompatibility of titanium can be used to achieve a safe composite osteogenesis of the anchoring part during the healing phase. The titanium applied, for example, by thermal spraying has sufficient fine structuring to avoid distance osteogenesis and to ensure safe ossification.

Preferably, only the area of the anchoring part that is sunk in the bone during the implantation is coated. This allows the advantageous aesthetics of zirconium oxide ceramics in the area of the abutment to be combined with the advantageous biocompatibility of titanium.

The mounting part expediently has a receptacle for attaching a screwing tool. In this case, the structural part can be designed for the positive reception of a screwing tool, as is basically already known.

The dental implant can in principle be designed in all known implant shapes or shapes to be developed.

Here, the structural part can be formed, for example, on an extension of the anchoring part or can be angled with respect to the anchoring part.

Likewise, the mounting part can have a frustoconical basic shape, which facilitates adhesive attachment of abutments to be built on for prosthesis constructions.

In addition, other shapes of the structural part are of course also conceivable, such as a square or hexagonal shape.

According to a further embodiment of the invention, after a previous activation of its surface, the dental implant is stored, for example by silanization, hydroxylation or by an etching treatment in a suitable liquid, for example deionized water, or in a NaCl solution until it is implanted by the doctor. The dental implant can thus be stored in a container, preferably with the exclusion of air.

In this way, it is avoided that the surface is affected by components of the air before the dental implant is inserted Activation completely or partially lost. This is how an osteo-integration is supported.

The production of the zirconium oxide ceramic for the one-piece dental implant is fundamentally known in the prior art and is regarded as not belonging to the invention. For this purpose, reference is made, for example, to US Pat. No. 6,165,925, the disclosure content of which is fully incorporated into the present application. A zirconium oxide ceramic produced in this way can be processed, for example, by grinding to the desired shape of the dental implant and then post-treated on its surface in order to achieve the desired surface quality.

It goes without saying that the features of the invention mentioned above and those yet to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own without departing from the scope of the present invention.

Further features and advantages result from the following description of preferred exemplary embodiments with reference to the drawing. Show it:

1 shows a view of a first embodiment of an implant according to the invention;

FIG. 2 shows a view of an embodiment of an implant according to the invention which is slightly modified from the embodiment of FIG. 1; 3 shows a view of a further embodiment of an implant according to the invention, in which the mounting part is slightly angled relative to the anchoring part;

Fig. 4 is a SEM on a test implant that was implanted in a patient and after a healing time of about 3 months was removed together with the surrounding bone substance using a drill.

FIGS. 1-3 show various possible embodiments of a one-piece dental implant according to the invention, without this being understood as restricting the shape of the implant.

A dental implant according to the invention is designated overall by the number 10 in FIG. 1. It has an anchoring part 12 with a threaded section 14 and a rounded lower end. The anchoring part 12 merges at its upper end via a section 16 which is slightly conically widened outwards into an integral part 18 formed therewith, which extends in the extension of the longitudinal axis 24 of the threaded section 14. The structural part 18 has a frustoconical or conical shape and is provided with a flat 20 on one side. On the side opposite the flat 20, a groove 22 is formed in the outer surface, which runs downward from the upper end face of the structural part 18 and ends in a conical section which forms the connection to the conical section 16 of the anchoring part 12. The flattened portion 20 is used in connection with the opposite groove 22 for the form-fitting attachment of a screwing tool which has a correspondingly adapted plug-in receptacle.

FIG. 2 shows a slightly modified embodiment of a dental implant designated overall by the number 30, again with an anchoring part 32 with a threaded section 34 and an adjoining conical structural part 38, on which the groove 42 can be seen, since the dental implant 30 is at 90 ° is arranged offset with respect to the dental implant 10 according to FIG. 1.

In contrast to the embodiment according to FIG. 1, the dental implant 30 has no conical section in the transition area between the anchoring part 32 and the mounting part 38. Rather, the structural part 38 directly adjoins the cylindrical anchoring part 32 as a conical section. A corresponding flattening, as can be seen in FIG. 1, can again be provided on the side opposite the groove 42.

A modified embodiment of a dental implant is designated by the number 50 in FIG. 3.

The dental implant 50 has an anchoring part 52 corresponding to the embodiment according to FIG. 1 with a threaded section 54, which merges into a mounting part 58 via an outer cone section 56.

The structural part 58 again has a conical basic shape, but is opposite the longitudinal axis of the anchoring part 52 angled, for example by an angle of about 15 °, which is particularly useful in many cases for use in the incisor area. A suitable recess 60 on an outer surface of the mounting part 58 in turn enables a form-fitting attachment of a screwing tool in order to be able to screw this dental implant with an angled mounting part into a bore in the bone.

The anchoring part can have an axial length of 10 mm, for example, the other dimensions resulting accordingly.

However, it goes without saying that the dimensioning and shape can be adapted in a suitable manner depending on the respective indication.

The dental implants 10, 30, 50 according to the invention are made in one piece from a zirconium oxide ceramic, for example a stabilized zirconium oxide ceramic with 92.1 to 93.5% by weight of ZrO ₂ and 4.5 to 5.5% by weight of Y. ₂ 0 ₃ and 1.8 to 2.2 wt .-% Hf0 _{2 can act} according to the aforementioned US 6,165,925. Such a stabilized zirconium oxide ceramic has an extraordinarily high mechanical stability and strength, in particular when manufactured by hot isostatic pressing or by sintering with subsequent ice isostatic post-compression. The use of any other zirconium oxide ceramics is also conceivable.

The anchoring part is treated by a suitable abrasive pretreatment or by a suitable coating on its outer surface, so as to ensure good composite osteogenesis after implantation. The anchoring part can, for example, be silanized or hydroxylated on its surface, or roughened or microstructured by a removal process.

A composite osteogenesis can likewise be achieved by means of a coating, which is preferably applied by thermal spraying with a layer thickness, preferably in the range between approximately 20 and 100 μm.

In addition to ceramic coatings, for example made of zirconium oxide, aluminum oxide, silicon oxide or mixtures thereof with optionally further proportions, a coating with pure titanium with a layer thickness between approximately 20 and 100 μm by thermal spraying is particularly preferred.

It is advisable to carry out a suitable pretreatment of the surface before spraying on the coating, for example in a plasma spraying process, in order to ensure good adhesion of the coating by sufficient roughness, e.g. by blasting or etching treatment.

A thin, thermally sprayed coating, in particular with titanium, only in the area of the anchoring part (outside the visible area) achieves reliable composite osteogenesis in the course of the healing time, while at the same time the advantages of zirconium oxide ceramics, such as grindability and staining that approximates the natural tooth, can be used.

Initial field tests have shown that a one-piece zirconium oxide implant, the outer surface of which is was subjected to a suitable ablative treatment that can guarantee composite osteogenesis.

For this purpose, test implants according to FIG. 4 were produced from a zirconium oxide ceramic according to the aforementioned US Pat. No. 6,165,925 and processed by grinding onto the shape according to FIG. 4.

The surface was then sandblasted with corundum at a pressure of 4 bar. This resulted in a maximum roughness depth of 6.4 μm with an average roughness depth of 4.7 μm. The test implant 70 shown in FIG. 4 was implanted in a patient. After a healing time of about 3 months, the test implant was removed with the help of a hollow drill together with a small proportion of the surrounding bone and examined histologically for osteointegration. It was shown that composite osteogenesis can be achieved.

Additional improvements with regard to composite osteogenesis after a short healing time are expected in particular from greater roughness depths in the order of magnitude of about 5 to 15 μm R _mΛX , for which post-treatment of the blasted surface by etching with phosphoric acid is particularly considered. For example, by etching with 30 percent phosphoric acid over a period of 30 seconds with subsequent rinsing, first with NaCl solution and then with deionized water, the roughness depth can be increased to approximately 5 to 15 μm R _^ (in particular approximately 8 to 12 μm, each after the previous blasting treatment). In addition, the activation of the surface achieved by etching supports osteointegration. In order to maintain this activation until the implantation, it is further preferred to store the implant in a suitable liquid, such as deionized water, until the implantation by the doctor immediately after the etching and rinsing treatment. In this way it is avoided that the surface loses its activation in whole or in part by components of the air before the dental implant is inserted.

Claims

claims 1. Dental implant with an anchoring part (12, 32, 52) for anchoring in the bone and with a build-up part (18, 38, 58) for receiving an element to be applied, the anchoring part (12, 32, 52) and build-up part (18, 38 , 58) are formed in one piece from a material based on zirconium oxide, and wherein at least the anchoring part (12, 32, 52) is at least partially pretreated on its outer surface by a subtractive, ablative process, or is provided with a coating which supports ossification becomes. 2. Dental implant according to claim 1, wherein the anchoring part (12, 32, 52) has a threaded portion (14, 34, 54). 3. Dental implant according to one of the preceding claims, in which the anchoring part (12, 32, 52) is at least partially roughened or microstructured on its outer surface by an ablation process. 4. Dental implant according to claim 3, in which the maximum roughness depth in the region of the anchoring part is between 1 and 20 μm, preferably between 2 and 15 μm, in particular between 4 and 12 μm, particularly preferably between 6 and 12 μm. 5. Dental implant according to claim 3, wherein the anchoring part (12, 32, 52) on its outer surface by a Blast treatment is treated, especially sandblasted. 6. Dental implant according to one of the preceding claims, wherein the anchoring part (12, 32, 52) is treated by etching. 7. Dental implant according to claim 6, wherein the anchoring part (12, 32, 52) is first processed by a radiation treatment and then by an etching treatment. 8. Dental implant according to one of claims 5 to 7, wherein the anchoring part (12, 32, 52) is blasted with a pressure between 1 bar and 10 bar, preferably between 2 bar and 6 bar, particularly preferably between 3 and 5 bar. 9. Dental implant according to claim 6, 7 or 8, wherein the anchoring part (12, 32, 52) is etched by means of phosphoric acid, sulfuric acid, hydrochloric acid or mixtures thereof. 10. Dental implant according to claim 9, in which the anchoring part (12, 32, 52) is etched by means of phosphoric acid from 10 to 90% by volume, preferably from 15 to 50% by volume, in particular from 20 to 40% by volume , 11. Dental implant according to one of claims 6 to 10, wherein the anchoring part (12, 32, 52) is etched over a period of 10 seconds to 10 minutes, preferably from 10 to 120 seconds, in particular from 15 to 60 seconds. 12. Dental implant according to one of claims 6 to 11, wherein the anchoring part (12, 32, 52) is cleaned after the etching, preferably first in NaCl solution and then rinsed in water. 13. Dental implant according to one of the preceding claims, in which the anchoring part (12, 32, 52) is at least partially provided on its outer surface with a bioactive coating. 14. Dental implant according to one of the preceding claims, in which the anchoring part (12, 32, 52) is silanized or hydroxylated. 15. Dental implant according to one of the preceding claims, wherein the anchoring part (12, 32, 52) is at least partially provided with a metallic or ceramic coating or with a cermet coating. 16. Dental implant according to claim 15, in which the anchoring part (12, 32, 52) is at least partially provided with a coating applied by thermal spraying, by CVD or PVD. 17. Dental implant according to claim 15, wherein the anchoring part (12, 32, 52) is at least partially provided with a thermally sprayed coating made of titanium or a titanium alloy. 18. Dental implant according to claim 15, wherein the anchoring part (12, 32, 52) at least partially with a thermal mixed sprayed coating of zirconium oxide, aluminum oxide, silicon oxide or mixtures thereof is provided. 19. Kit with a sealable container with a liquid, preferably water, in which a dental implant according to one of the preceding claims is received. 20. A method for producing a dental implant, in which a base body with an anchoring part (12, 32, 52) for anchoring in the bone and with a mounting part (18, 38, 58) for receiving an element to be applied in one piece from a material based on zirconium oxide is provided, and then at least the anchoring part (12, 32, 52) on its outer surface is at least partially pretreated by a subtractive, ablative process or is provided with a coating which supports ossification. 21. The method according to claim 20, wherein the anchoring part (12, 32, 52) is blasted on its outer surface, preferably sandblasted. 22. The method of claim 20 or 21, wherein the anchoring part (12, 32, 52) is etched on its outer surface, preferably by means of phosphoric acid, sulfuric acid, hydrochloric acid or mixtures thereof, in particular first sandblasted and then etched with phosphoric acid. 3. The method according to any one of claims 20 to 22, wherein the outer surface of the anchoring part (12, 32, 52) is provided with a coating of titanium or a titanium alloy, preferably by thermal spraying.